1. Field of the Invention
The present invention relates to a brushless motor.
2. Description of the Related Art
In the conventional practice, motors are used as driving sources of various types of apparatuses and products. For example, the motors are used for business machines, such as printers and copying machines, various kinds of home electric appliances, and power assist sources of vehicles, such as automobiles and power-assisted bicycles. In particular, brushless motors are sometimes used as the driving sources of movable parts with high operation frequency in the light of increased durability and reduced noise.
A brushless motor of inner rotor type is known. A stator is disposed around a rotor and coils are wound around a plurality of stator teeth provided in the stator. Various methods for winding coils around a plurality of stator teeth are known. For example, a synchronous machine in which the coils are delta-connected or start-connected is disclosed (see patent document 1).
[patent document 1] JP2012-517209
In one type of synchronous machines, a delta connection is achieved by continuous wire connection. Continuous connection requires a large number of connecting wires that bridge stator teeth of the same phase at a distance from each other and so requires spaces for disposing connecting wires, and substitute components such as bus bars. Because connecting wires do not generate a magnetic force in the stator that contributes to the motor property, the number of connecting wires is preferably reduced as much as possible.